In recent years the compounds 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (lomustine, CCNU) and 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) have been found effective as cytostatic agents in the treatment of various tumors, either alone or in combination with other cytostatic drugs.
Unfortunately, they also have serious untoward side effects and are rather toxic compounds, and the therapeutic index, the ratio between the toxic dose and the therapeutic dose, is not very favorable.